Michael Schumacher's skiing accident was a freak fall down to "extreme bad luck", according to his manager Sabine Kehm.

Schumacher fell in the resort of Meribel on Sunday, hitting his head on a rock in a patch of deep snow between pistes. He was quickly helicoptered to a local hospital before being transferred to a larger hospital in Grenoble where he is currently undergoing treatment.

On Tuesday, Kehm, who was not on the slopes at the time of the accident, gave an account of what she had managed to piece together from witnesses.

"Having spoken to several people who were with Michael at this moment, Michael and the group had been skiing on normal slopes and then between a red slope and blue slope was a part with deep snow," she told reporters. "Michael went into that, but after everything that people told me, it was not even at high speed.

"It seemed he had just helped a friend who had fallen and started to ski again, went into this deep snow and apparently - this is what we guess - hit a rock as he tried to do a turn and was catapulted in the air and landed head down on another rock. It was extreme bad luck and circumstances, and not because he was speeding too much. I have spoken with several people, including ski teachers, that tell me that can happen even at 10km/h. It was just very, very unfortunate."

Schumacher's condition remains critical but has improved since Monday after overnight surgery.

The International Rugby Board (IRB) have stripped Australia of the right to host a round of the World Sevens Series, scheduled for Brisbane on 16-17 February, after the Australian government's refusal to provide visas for the squad from Fiji